1. Field of the Invention
The present invention relates to a process for producing a piezoelectric ceramic sheet and a dielectric ceramic sheet used as an electrical part.
2. Description of Related Art
An improvement in the degree of displacement is desirable for a material, when a piezoelectric ceramic is utilized as an actuator, and accordingly, such an improvement has been generally made in the art through studies of the composition of the material. Specifically, the studies began with the use of barium titanate, and the discovery of a large electromechanical coupling factor in a PbTiO.sub.3 -PbZrO.sub.3 system has led to remarkable advances in the practicability thereof. Further, after a proposal of a PbTiO.sub.3 -PbZrO.sub.3 -Pb(Mg.sub.1 /3Nb.sub.2/3)O.sub.3 system, investigations of the effect of various third components and additives have been conducted and have produced excellent results. In recent years, however, no particular improvement has been made in the art.
On the other hand, an attempt has been made to obtain an improvement in the degree of displacement through an increase in the orientation of the crystal without a change in the composition. For example, when a particle having an anisotropic shape is molded, the molded body becomes orientated. Nevertheless, when the molded body is fired, the orientation is lost, and thus no improvement in the performance can be realized.
Accordingly, an object of the present invention is to provide a process for producing a piezoelectric ceramic sheet having an improved degree of piezoelectric displacement.
Another object of the present invention is to provide a process for producing a Pb-based dielectric ceramic having an improved dielectric constant.